Efficacy and Safety of MEDI2070, an Antibody Against Interleukin 23, in Patients With Moderate to Severe Crohn's Disease: A Phase 2a Study

All are Equal, Some are More Equal: Targeting IL 12 and 23 in IBD - A Clinical Perspective

Chronic inflammatory diseases like inflammatory bowel diseases (IBD) or psoriasis represents a worldwide health burden. Researchers provided great achievements in understanding the origin of these diseases leading to improved therapeutic options. The discovery of cytokines like tumor necrosis factor-α or transforming growth factor-β are examples for these efforts. Interleukin 12 (IL 12) and interleukin 23 (IL 23) represent different important cytokines in this regard. They both belong to the interleukin 12 family and are related by sharing the subunit p40. Ustekinumab is an antibody that blocks p40 and thereby interleukins 12 and 23. Trials showed promising results in treating IBD patients with this drug. Consequently, new questions arose about the distinct features of IL 12 and 23. This review focuses on these interleukins regarding their functions in the healthy and inflamed gut and provides an overview about the results from in vitro and in vivo studies as well as clinical trials.

Metabolic Regulation of Group 3 Innate Lymphoid Cells and Their Role in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is characterized by chronic and relapsing inflammatory disorder of the intestine. IBD is associated with complex pathogenesis, and considerable data suggest that innate lymphoid cells contribute to the development and progression of the condition. Group 3 innate lymphoid cells (ILC3s) not only play a protective role in maintaining intestinal homeostasis and gut barrier function, but also a pathogenic role in intestinal inflammation. ILC3s can sense environmental and host-derived signals and combine these cues to modulate cell expansion, migration and function, and transmit information to the broader immune system. Herein, we review current knowledge of how ILC3s can be regulated by dietary nutrients, microbiota and their metabolites, as well as other metabolites. In addition, we describe the phenotypic and functional alterations of ILC3s in IBD and discuss the therapeutic potential of ILC3s in the treatment of IBD.

Current Status of Medical Therapy for Inflammatory Bowel Disease: The Wealth of Medications

Previously, the natural history of Crohn's disease and ulcerative colitis included significant morbidity due to limited treatment options that were not without serious side effects. Early treatment options included corticosteroids as well as mesalamine, thiopurines, and methotrexate. In 1998, monoclonal antibodies to a key inflammatory cytokine, TNFα, became available. Over the next 22 years, the field of gastroenterology has seen multiple new treatments emerging for inflammatory bowel disease (IBD) that target different aspects of the inflammatory cascade, significantly changing the therapeutic landscape. Additional monoclonal antibodies are available that target the integrins, which are adhesion proteins that traffic inflammatory leukocytes. Small molecule inhibitors block the inflammatory signals of several cytokines. New therapies that modulate lymphocyte escape from lymphoid tissue are promising. Lastly, stem cell technology has emerged as a platform to successfully treat perianal fistulizing disease. Our aim is to summarize the currently available therapies for IBD beyond steroids, mesalamine, and immune modulators. We highlight the most important clinical trials that have brought these treatments to clinical practice, and we discuss the ongoing clinical trials of novel therapies that have a high probability of eventual regulatory approval.

Biomarkers of Crohn's Disease to Support the Development of New Therapeutic Interventions

BACKGROUND

Currently, 2 coprimary end points are used by health authorities to determine the effectiveness of therapeutic interventions in patients with Crohn's disease (CD): symptomatic remission (patient-reported outcome assessment) and endoscopic remission (ileocolonoscopy). However, there is lack of accepted biomarkers to facilitate regulatory decision-making in the development of novel therapeutics for the treatment of CD.

METHODS

With support from the Helmsley Charitable Trust, Critical Path Institute formed the Crohn's Disease Biomarkers preconsortium (CDBpC) with members from the pharmaceutical industry, academia, and nonprofit organizations to evaluate the CD biomarker landscape. Biomarkers were evaluated based on biological relevance, availability of biomarker assays, and clinical validation data.

RESULTS

The CDBpC identified the most critical need as pharmacodynamic/response biomarkers to monitor disease activity in response to therapeutic intervention. Fecal calprotectin (FC) and serum C-reactive protein (CRP) were identified as biomarkers ready for the regulatory qualification process. A number of exploratory biomarkers and potential panels of these biomarkers was also identified for additional development. Given the different factors involved in CD and disease progression, a combination of biomarkers, including inflammatory, tissue injury, genetic, and microbiome-associated biomarkers, will likely have the most utility.

CONCLUSIONS

The primary focus of the Inflammatory Bowel Disease Regulatory Science Consortium will be development of exploratory biomarkers and the qualification of FC and CRP for IBD. The Inflammatory Bowel Disease Regulatory Science Consortium, focused on tools to support IBD drug development, will operate in the precompetitive space to share data, biological samples for biomarker testing, and assay information for novel biomarkers.

A Dynamic Quantitative Systems Pharmacology Model of Inflammatory Bowel Disease: Part 2 - Application to Current Therapies in Crohn's Disease

Inflammatory bowel disease (IBD) is a heterogeneic disease with a variety of treatments targeting different mechanisms. A multistate, mechanistic, mathematical model of IBD was developed in part 1 of this two-part article series. In this paper, application of the model to predict response of key clinical biomarkers following different treatment options for Crohn's disease was explored. Five therapies, representing four different mechanisms of action, were simulated in the model and longitudinal profiles of key clinical markers, C-reactive protein and fecal calprotectin were compared with clinical observations. Model simulations provided an accurate match with both central tendency and variability observed in biomarker profiles. We also applied the model to predict biomarker and clinical response in an experimental, combination therapy of existing therapeutic options and provide possible mechanistic basis for the increased response. Overall, we present a validated, modular, mechanistic model construct, which can be applied to explore key biomarkers and clinical outcomes in IBD.

The risk of respiratory tract infections and interstitial lung disease with interleukin 12/23 and interleukin 23 antagonists in patients with autoimmune diseases: A systematic review and meta-analysis

Background

Respiratory tract infections (RTIs) and interstitial lung disease (ILD) secondary to interleukin (IL) 12/23 or IL-23 antagonists have been reported in autoimmune diseases.

Objective

To assess the risk of RTIs and noninfectious ILD with these drugs.

Methods

We conducted a systematic review and meta-analysis of randomized controlled trials. Risk of RTIs and noninfectious ILD was compared to placebo by Mantel-Haenszel risk difference. We divided RTIs into upper RTIs (URTI), viral URTIs, and lower RTIs (LRTIs) including infectious pneumonia. Noninfectious ILD included ILD, eosinophilic pneumonia, and pneumonitis.

Results

We identified 54 randomized controlled trials including 10,907 patients with 6 IL-12/23 or IL-23 antagonists and 5175 patients with placebo. These drugs significantly increased the risk of RTIs (Mantel-Haenszel risk difference, 0.019; 95% confidence interval, 0.005-0.033; P = .007), which was attributed to URTIs, but not viral URTIs or LRTIs. There was no significant difference in infectious pneumonia and noninfectious ILD between 2 groups.

Limitations

Because of the rarity of infectious pneumonia and ILD, sensitivity analysis was required.

Conclusions

The use of IL-12/23 or IL-23 antagonists for autoimmune diseases increased the risk of URTIs, but not viral URTIs, LRTIs, and noninfectious ILD.

Secukinumab-Induced Inflammatory Bowel Disease in a Patient Treated for Chronic Plaque Psoriasis and Psoriatic Arthritis: A Case Report and Review of the Role of Novel Biologic Agents Targeting the p19 Subunit of IL-23

Chronic plaque psoriasis and psoriatic arthritis are common autoimmune inflammatory conditions, often existing as comorbidities that have a significant impact on a patient's quality of life. The availability of a range of novel, targeted therapies for their treatment, most notably the availability of biologic agents, has revolutionised management of these conditions and allowed for significant improvements in patient outcomes. Secukinumab (Cosentyx), a fully-human monoclonal antibody that acts by selectively binding to and neutralising the proinflammatory cytokine IL-17A, is used widely for the treatment of both chronic plaque psoriasis and psoriatic arthritis. In this report, we discuss the case of a 54-year-old female with chronic plaque psoriasis and psoriatic arthritis, who experienced the onset of symptoms and was subsequently diagnosed with Crohn's disease during treatment with secukinumab. It was determined by the gastroenterologist that this may represent secukinumab-induced inflammatory bowel disease. We will review the current understanding of the role of IL-17 in inflammatory bowel disease and the important role of novel agents that target the p19 subunit of IL-23 which have shown significant promise in the management of not only chronic plaque psoriasis and psoriatic arthritis, but also inflammatory bowel disease itself.

Targeting interleukin-17 in chronic inflammatory disease: A clinical perspective

Although many chronic inflammatory diseases share the feature of elevated IL-17 production, therapeutic targeting of IL-17 has vastly different clinical outcomes. Here the authors summarize the recent progress in understanding the protective and pathogenic role of the IL-23/IL-17 axis in preclinical models and human inflammatory diseases.

Chronic inflammatory diseases like psoriasis, Crohn’s disease (CD), multiple sclerosis (MS), rheumatoid arthritis (RA), and others are increasingly recognized as disease entities, where dysregulated cytokines contribute substantially to tissue-specific inflammation. A dysregulation in the IL-23/IL-17 axis can lead to inflammation of barrier tissues, whereas its role in internal organ inflammation remains less clear. Here we discuss the most recent developments in targeting IL-17 for the treatment of chronic inflammation in preclinical models and in patients afflicted with chronic inflammatory diseases.

Personalised medicine in Crohn's disease

Similar to many immune-mediated diseases, Crohn's disease follows a relapsing-remitting pattern, with a variable disease course and heterogeneous clinical outcomes. Frequency of flare-ups, development of complications, and response to treatment collectively determine the effect on a patient's quality of life, which can vary from minimal disruption to profound disability or death. Despite recent advances in the understanding of complex disease pathogenesis, including for Crohn's disease, management decisions are still typically made using a one-size-fits-all approach. Indeed, the inability to reliably predict clinical outcomes in a way that could guide future therapy represents a major unmet need. Recently, several important insights have been made into the biology underlying outcomes in Crohn's disease. In this Review, we will summarise these insights and discuss how greater understanding of these disease mechanisms can be used to develop clinically useful biomarkers, identify novel approaches to optimise disease control, and help deliver the goal of personalised medicine.

Discordance Between Patient-Reported Outcomes and Mucosal Inflammation in Patients With Mild to Moderate Ulcerative Colitis

BACKGROUND & AIMS

Little is known about the association between rectal bleeding and increased stool frequency with endoscopic findings in patients with mild to moderate ulcerative colitis (UC). We evaluated the associations between rectal bleeding or stool frequency and endoscopic remission in this population.

METHODS

We performed a post-hoc analysis of data from a phase 3 non-inferiority trial of 817 adults with mild to moderate UC who received treatment with mesalazine. We obtained information on rectal bleeding, stool frequency, and Mayo endoscopic subscores (MESs) at weeks 0, 8, and 38. The sensitivity, specificity, and positive and negative predictive values with which rectal bleeding and stool frequency identified patients with MESs of 0 and/or 1 were calculated at weeks 8 and 38 of treatment. The associations between change in rectal bleeding and stool frequency and change in MES after treatment were quantified using the Spearman's rank correlation coefficient.

RESULTS

Among patients with a MES of 0, 7/82 patients (9%) had a rectal bleeding score of 1 or more and 40/82 patients (49%) had a stool frequency score of 1 or more at week 8; at week 38, 6/167 patients (4%) had a rectal bleeding score of 1 or more and 63/167 patients (38%) had a stool frequency score of 1 or more. Among patients with MESs of 0 or 1, 50/310 patients (16%) had a rectal bleeding score of 1 or more and 162/310 patients (52%) had had a stool frequency score of 1 or more at week 8; at week 38, 18/363 patients (5%) had a rectal bleeding score of 1 or more and 141/363 patients (39%) had a stool frequency score of 1 or more. The Spearman rank correlation coefficients for change in rectal bleeding and stool frequency with change in MES at week 8 were 0.39 (95% CI, 0.32-0.45) and 0.34 (95% CI, 0.27-0.40), respectively. In patients with reduced MESs at week 8, 39/389 patients (10%) had unchanged or worsening rectal bleeding and 81/389 patients (21%) had unchanged or increasing stool frequencies.

CONCLUSIONS

In a post-hoc analysis of data from a phase 3 trial of adults with mild to moderate UC treated with mesalazine, we found absence of rectal bleeding to identify patients in endoscopic remission. However, many patients in remission still have increased stool frequency, indicating that it may not be a sensitive marker of disease activity in patients with mild to moderate UC.

IL23 Promotes Antimicrobial Pathways in Human Macrophages, Which Are Reduced With the IBD-Protective IL23R R381Q Variant

BACKGROUND & AIMS

Interleukin (IL)23 is a major contributor to inflammatory bowel disease (IBD) pathogenesis and is being pursued as a therapeutic target, both through targeting IL23 alone or in combination with IL12. Unexpected trial outcomes highlight the importance of understanding the cell types through which IL23 regulates immune responses, and how IL23 and IL12 compare in these responses. Macrophages are key players in IBD, and IL23 recently was found to promote inflammatory outcomes in human macrophages. This raises the possibility that IL23 may be required for additional essential macrophage functions, in particular microbial clearance, such that either blocking the IL23 pathway or the IL23R-R381Q IBD-protective variant may reduce macrophage-mediated microbial clearance.

METHODS

We analyzed protein expression, signaling, bacterial uptake, and intracellular bacterial clearance in human monocyte-derived macrophages through Western blot, flow cytometry, and gentamicin protection.

RESULTS

Autocrine/paracrine IL23 was critical for optimal levels of pattern-recognition-receptor (PRR)-induced intracellular bacterial clearance in human macrophages. Mechanisms regulated by IL23 included induction of pyruvate dehydrogenase kinase 1-dependent bacterial uptake, and up-regulation of reactive oxygen species through nicotinamide adenine dinucleotide phosphate oxidase members, nitric oxide synthase 2, and autophagy through ATG5 and ATG16L1. Complementing these pathways in IL23R-deficient macrophages restored PRR-induced bacterial uptake and clearance. Janus kinase 2, TYK2, and STAT3 were required for IL23-induced mechanisms. IL23 and IL12 induced antimicrobial pathways to similar levels in human macrophages. Relative to IL23R-R381, transfected IL23R-Q381, or monocyte-derived macrophages from IL23R-Q381 carriers showed reduced bacterial uptake and clearance.

CONCLUSIONS

We identify that autocrine/paracrine IL23 is required for optimal PRR-enhanced macrophage bacterial uptake and intracellular bacterial clearance, define mechanisms regulating IL23R-induced bacterial clearance, and determine how the IBD-protective IL23R-R381Q variant modulates these processes.

Cytokines in inflammatory bowel diseases - Update 2020

Inflammatory Bowel Diseases (IBD), namely Crohn's Disease and Ulcerative Colitis, cause a significant disease burden in modern civilization. Ever since the introduction of anti-TNF-directed therapies 20 years ago, cytokines have attracted a lot of research attention and several cytokine-directed therapies have been implemented in the clinical treatment of these diseases. The research progress in these past years has underlined the importance of both myeloid and lymphoid elements of the immune system in the pathogenesis of IBD and their cytokine-mediated interplay. The conceptual framework of the mucosal cytokine network has shifted during these years from a T helper (Th) dichotomy (Th1/Th2) to the effector/regulatory T cell balance, while nowadays, the importance of myeloid cell instruction of lymphocytes, namely by IL-12 and IL-23, is increasingly recognized. Anti-IL-12p40 agents, like ustekinumab, groundbreakingly changed patient care, and anti-IL23p19-directed approaches are on the verge of grand success. In this review we present a modular approach to understand the cytokine network and put it into the context of the pathogenesis of IBD with a special focus on publications since 2014.

Perspectives on Current and Novel Treatments for Inflammatory Bowel Disease

New therapeutic strategies in inflammatory bowel disease (IBD) have shifted from symptom control towards treat-to-target algorithms in order to optimize treatment results. The treatment of IBD has evolved with the development of tumor necrosis factor-α inhibitors beyond the conventional therapies. In spite of their long-term effectiveness, many patients do not respond to or cannot sustain treatment with these drugs, which have various side effects. Therefore, the development of new drugs targeting specific pathways in the pathogenesis of IBD has become necessary. Some novel biologics and small molecule drugs have shown potential in IBD clinical trials, providing safe and effective results. In addition, clinicians are now trying to target the dysbiotic microbiome of patients with IBD using fecal microbiota transplantation. New tools such as stem cells have also been developed. The available therapeutic options for IBD are expanding rapidly. In the next few years, physicians will face an unprecedented number of options when choosing the best treatments for patients with IBD. This review provides an overview of recent advances in IBD treatment options.

Serum Biomarkers for Inflammatory Bowel Disease

Background: Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic, inflammatory disorder of the gastrointestinal tract. As the novel therapeutic goal and biologicals are widely recognized, accurate assessment of disease and prediction of therapeutic response have become a crucial challenge in clinical practice. Also, because of the continuously rising incidence, convenient and economical methods of diagnosis and clinical assessment are urgently needed. Recently, serum biomarkers have made a great progress and become a focus in IBD study because they are non-invasive, convenient, and relatively inexpensive than are markers in biopsy tissue, stool, breath, and other body fluids.

Aims: To review the available data on serological biomarkers for IBD.

Methods: We searched PubMed using predefined key words on relevant literatures of serum biomarkers regarding diagnosis, evaluation of therapeutic efficacy, surveillance of disease activity, and assessment of prognosis for IBD.

Results: We reviewed serological biomarkers that are well-established and widely used (e.g., C-reactive protein), newly discovered biomarkers (e.g., cytokines, antibodies, and non-coding RNAs), and also recently advancements in serological biomarkers (e.g., metabolomics and proteomics) that are used in different aspects of IBD management.

Conclusions: With such a wealth of researches, to date, there are still no ideal serum biomarkers for IBD. Serum profiling and non-coding RNAs are just starting to blossom but reveal great promise for future clinical practice. Combining different biomarkers can be valuable in improving performance of disease evaluation.

BATF2 prevents T-cell-mediated intestinal inflammation through regulation of the IL-23/IL-17 pathway

Inappropriate activation of the IL-23 signaling pathway causes chronic inflammation through the induction of immunopathological Th17 cells in several tissues including the intestine, whereas adequate Th17 responses are essential for host defense against harmful organisms. In the intestinal lamina propria, IL-23 is primarily produced by innate myeloid cells including dendritic cells (DCs) and macrophages (Mϕs). However, the molecular mechanisms underlying the regulation of IL-23 production by these cells remains poorly understood. In this study, we demonstrated that BATF2 regulates intestinal homeostasis by inhibiting IL-23-driven T-cell responses. Batf2 was highly expressed in intestinal innate myeloid subsets, such as monocytes, CD11b+ CD64+ Mϕs and CD103+ DCs. Batf2-/- mice spontaneously developed colitis and ileitis with altered microbiota composition. In this context, IL-23, but not TNF-α and IL-10, was produced in high quantities by intestinal CD11b+ CD64+ Mϕs from Batf2-/- mice compared with wild-type mice. Moreover, increased numbers of IFN-γ+, IL-17+ and IFN-γ+ IL-17+ CD4+ T cells, but not IL-10+ CD4+ T cells, accumulated in the colons and small intestines of Batf2-/- mice. In addition, RORγt-expressing innate lymphoid cells were increased in Batf2-/- mice. Batf2-/-Rag2-/- mice showed a reduction in intestinal inflammation present in Batf2-/- mice. Furthermore, the high numbers of intestinal IL-17+ and IFN-γ+ IL-17+ CD4+ T cells were markedly reduced in Batf2-/- mice when introducing Il23a deficiency, which was associated with the abrogation of intestinal inflammation. These results indicated that BATF2 in innate myeloid cells is a key molecule for the suppression of IL-23/IL-17 pathway-mediated adaptive intestinal pathology.

Crohn's disease

Crohn's disease is an inflammatory bowel disease that is characterized by chronic inflammation of any part of the gastrointestinal tract, has a progressive and destructive course and is increasing in incidence worldwide. Several factors have been implicated in the cause of Crohn's disease, including a dysregulated immune system, an altered microbiota, genetic susceptibility and environmental factors, but the cause of the disease remains unknown. The onset of the disease at a young age in most cases necessitates prompt but long-term treatment to prevent disease flares and disease progression with intestinal complications. Thus, earlier, more aggressive treatment with biologic therapies or novel small molecules could profoundly change the natural history of the disease and decrease complications and the need for hospitalization and surgery. Although less invasive biomarkers are in development, diagnosis still relies on endoscopy and histological assessment of biopsy specimens. Crohn's disease is a complex disease, and treatment should be personalized to address the underlying pathogenetic mechanism. In the future, disease management might rely on severity scores that incorporate prognostic factors, bowel damage assessment and non-invasive close monitoring of disease activity to reduce the severity of complications.

Interleukin 23 and autoimmune diseases: current and possible future therapies

PURPOSE

IL-23 is a central proinflammatory cytokine with a wide range of influence over immune response. It is implicated in several autoimmune diseases due to the infinite inflammatory loops it can create through the positive feedbacks of both IL-17 and IL-22 arms. This made IL-23 a key target of autoimmune disorders therapy, which indeed was proven to inhibit inflammation and ameliorate diseases. Current autoimmune treatments targeting IL-23 are either by preventing IL-23 ligation to its receptor (IL-23R) via antibodies or inhibiting IL-23 signaling by signaling downstream mediators' inhibitors, with each approach having its own pros and cons.

METHODS

Literature review was done to further understand the biology of IL-23 and current therapies.

RESULTS

In this review, we discuss the biological features of IL-23 and its role in the pathogenesis of autoimmune diseases including psoriasis, rheumatoid arthritis and inflammatory bowel diseases. Advantages, limitations and side effects of each concept will be reviewed, suggesting several advanced IL-23-based bio-techniques to generate new and possible future therapies to overcome current treatments problems.

New insights into the IL-12 and IL-23: From a molecular basis to clinical application in immune-mediated inflammation and cancers

The cytokines interleukin-12 (IL-12) and IL-23 share a common IL-12/IL-23p40 subunit in structure and play a central role in T cell-mediated responses in inflammation. Over-activated IL-12 and IL-23 signaling drives aberrant T helper (Th) 1 and Th17 immune responses and contributes to immune-mediated diseases. Evidence from genome-wide association studies has shown that genetic alterations in the IL-12/IL-23 signaling pathways have significant links with chronic inflammation. In addition, accumulating evidence from animal models and clinical trials has provided insights into the effectiveness of blocking the IL-12/IL-23 pathways in immune regulation, broadening the clinical indications of IL-12/IL-23 pathway effectors in immune-mediated diseases. More recently, it has been addressed that the balance between IL and 12 and IL-23 is also critical in carcinogenesis. IL-12- and IL-23-driven T cell cytokines are especially important in controlling tumor initiation, growth, and metastasis, and thus, the IL-12/IL-23 pathway may be a promising target for immunotherapy. This review focuses on IL-12/IL-23 signal transduction and biological functionality in autoimmunity and oncoimmunology. We discuss the therapeutic rationale for targeting these cytokines to treat immune-mediated diseases and issues regarding their inadvertent consequences in the balance of host defense and tumor surveillance and summarize their recent clinical applications in immune-mediated diseases.

Efficacy and Safety of Biologics for Psoriasis and Psoriatic Arthritis and Their Impact on Comorbidities: A Literature Review

Psoriasis is a chronic inflammatory skin disease characterized by scaly indurated erythema. It impairs patients’ quality of life enormously. It has been recognized not only as a skin disease but as a systemic disease, since it also causes arthritis (psoriatic arthritis) and mental disorders. Furthermore, an association with cardiovascular events is indicated. With the advent of biologics, treatment of psoriasis dramatically changed due to its high efficacy and tolerable safety. A variety of biologic agents are available for the treatment of psoriasis nowadays. However, characteristics such as rapidity of onset, long-term efficacy, safety profile, and effects on comorbidities are different. Better understanding of those characteristic leads to the right choice for individual patients, resulting in higher persistence, longer drug survival, higher patient satisfaction, and minimizing the disease impact of psoriasis. In this paper, we focus on the efficacy and safety profile of biologics in psoriasis patients, including plaque psoriasis and psoriatic arthritis. In addition, we discuss the impact of biologics on comorbidities caused by psoriasis.

Interleukin-22 orchestrates a pathological endoplasmic reticulum stress response transcriptional programme in colonic epithelial cells

OBJECTIVE

The functional role of interleukin-22 (IL22) in chronic inflammation is controversial, and mechanistic insights into how it regulates target tissue are lacking. In this study, we evaluated the functional role of IL22 in chronic colitis and probed mechanisms of IL22-mediated regulation of colonic epithelial cells.

DESIGN

To investigate the functional role of IL22 in chronic colitis and how it regulates colonic epithelial cells, we employed a three-dimentional mini-gut epithelial organoid system, in vivo disease models and transcriptomic datasets in human IBD.

RESULTS

As well as inducing transcriptional modules implicated in antimicrobial responses, IL22 also coordinated an endoplasmic reticulum (ER) stress response transcriptional programme in colonic epithelial cells. In the colon of patients with active colonic Crohn's disease (CD), there was enrichment of IL22-responsive transcriptional modules and ER stress response modules. Strikingly, in an IL22-dependent model of chronic colitis, targeting IL22 alleviated colonic epithelial ER stress and attenuated colitis. Pharmacological modulation of the ER stress response similarly impacted the severity of colitis. In patients with colonic CD, antibody blockade of IL12p40, which simultaneously blocks IL12 and IL23, the key upstream regulator of IL22 production, alleviated the colonic epithelial ER stress response.

CONCLUSIONS

Our data challenge perceptions of IL22 as a predominantly beneficial cytokine in IBD and provide novel insights into the molecular mechanisms of IL22-mediated pathogenicity in chronic colitis. Targeting IL22-regulated pathways and alleviating colonic epithelial ER stress may represent promising therapeutic strategies in patients with colitis.

TRIAL REGISTRATION NUMBER

NCT02749630.

Inflammatory bowel disease: between genetics and microbiota

Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disease that can involve any part of the gastrointestinal tract. It includes two main disorders: Crohn's disease (CD) and Ulcerative colitis (UC). CD and UC often share a similar clinical presentation; however, they affect distinct parts of the GI Tract with a different gut wall inflammatory extent. Ultimately, IBD seems to emanate from an uncontrollably continuous inflammatory process arising against the intestinal microbiome in a genetically susceptible individual. It is a multifactorial disease stemming from the impact of both environmental and genetic components on the intestinal microbiome. Furthermore, IBD genetics has gained a lot of attention. Around 200 loci were identified as imparting an increased risk for IBD. Few of them were heavily investigated and determined as highly linked to IBD. These genes, as discussed below, include NOD2, ATG16L1, IRGM, LRRK2, PTPN2, IL23R, Il10, Il10RA, Il10RB, CDH1 and HNF4α among others. Consequently, the incorporation of a genetic panel covering these key genes would markedly enhance the diagnosis and evaluation of IBD.

Interleukin-23 Blockers: Born to be First-line Biologic Agents in Inflammatory Bowel Disease?

Over the past decades, the advent of anti-TNF agents has dramatically changed the treatment algorithms for IBD. However, primarily and more importantly, secondary loss of response to anti-TNF agents, is often observed. Thus, new treatment options have been actively explored and some have already been incorporated in the current clinical practice. Among the class of anti-cytokine agents, the anti-IL12/IL23 monoclonal antibodies (mAbs) have been first presented, in clinical practice, by the anti-p40 mAb ustekinumab in Crohn's disease (CD). More selective anti-IL23 agents (anti-p19) have shown efficacy and are being further developed, in contrast to agents inhibiting IL-17 downstream, which have failed in IBD clinical trials despite their clear efficacy in psoriasis.

Are We Ready to Include Prognostic Factors in Inflammatory Bowel Disease Trials?

Inflammatory bowel disease (IBD) is a chronic inflammatory disease characterized by periodic episodes of flares and remission. Treatment is aimed at healing the bowel, to ultimately decrease hospitalization rates, need for surgeries and overall disability. In more recent years, treatment has transitioned from a reactive approach to a more proactive approach focusing on treating disease earlier and preventing complications. The challenge lies in identifying patients who need more intensive treatment early and trying to determine who will respond to which medications. Biomarkers and clinical activity scoring systems can be used to help guide treatment decisions. However, IBDs are very heterogeneous and the significance of these biomarkers can be difficult to discern on an individual basis. Recently, prognostic tools have been developed to aid in determining a patient's prognosis as well as their likelihood to respond to different therapies. Despite this progress, clinical trials have not routinely adopted this approach in their study design. Tools for stratification of disease severity and to personalize treatment choices have the potential to improve our studies both by enriching the patient population and further guiding clinical decision making in practice. This review aims to discuss biomarkers, current prognosticating tools, tools that determine response to therapy and how incorporating these into clinical trials will be beneficial.

IL23 induces IL23R recycling and amplifies innate receptor-induced signalling and cytokines in human macrophages, and the IBD-protective IL23R R381Q variant modulates these outcomes

OBJECTIVE

The interleukin (IL)23 pathway contributes to IBD pathogenesis and is being actively studied as a therapeutic target in patients with IBD. Unexpected outcomes in these therapeutic trials have highlighted the importance of understanding the cell types and mechanisms through which IL23 regulates immune outcomes. How IL23 regulates macrophage outcomes and the consequences of the IL23R R381Q IBD-protective variant on macrophages are not well defined; macrophages are key players in IBD pathogenesis and inflammation.

DESIGN

We analysed protein and RNA expression, signalling and localisation in human monocyte-derived macrophages (MDMs) through western blot, ELISA, real-time PCR, flow cytometry, immunoprecipitation and microscopy.

RESULTS

IL23R was critical for optimal levels of pattern-recognition receptor (PRR)-induced signalling and cytokines in human MDMs. In contrast to the coreceptor IL12Rβ1, IL23 induced dynamic IL23R cell surface regulation and this required clathrin and dynamin-mediated endocytosis and endocytic recycling-dependent pathways; these pathways were essential for IL23R-mediated outcomes. The IBD-protective IL23R R381Q variant showed distinct outcomes. Relative to IL23R R381, HeLa cells expressing IL23R Q381 showed decreased IL23R recycling and reduced assembly of IL23R Q381 with Janus kinase/signal transducer and activator of transcription pathway members. In MDMs from IL23R Q381 carriers, IL23R accumulated in late endosomes and lysosomes on IL23 treatment and cells demonstrated decreased IL23R- and PRR-induced signalling and cytokines relative to IL23R R381 MDMs.

CONCLUSION

Macrophage-mediated inflammatory pathways are key contributors to IBD pathogenesis, and we identify an autocrine/paracrine IL23 requirement in PRR-initiated human macrophage outcomes and in human intestinal myeloid cells, establish that IL23R undergoes ligand-induced recycling, define mechanisms regulating IL23R-induced signalling and determine how the IBD-protective IL23R R381Q variant modulates these processes.

Efficacy and Safety of Mirikizumab in a Randomized Phase 2 Study of Patients With Ulcerative Colitis

BACKGROUND & AIMS

Interleukin 23 contributes to the pathogenesis of ulcerative colitis (UC). We investigated the effects of mirikizumab, a monoclonal antibody against the p19 subunit of interleukin 23, in a phase 2 study of patients with UC.

METHODS

We performed a trial of the efficacy and safety of mirikizumab in patients with moderate to severely active UC, enrolling patients from 14 countries from January 2016 through September 2017. Patients were randomly assigned to groups given intravenous placebo (N = 63), mirikizumab 50 mg (N = 63) or 200 mg (N = 62) with exposure-based dosing, or mirikizumab 600 mg with fixed dosing (N = 61) at weeks 0, 4, and 8. Of assigned patients, 63% had prior exposure to a biologic agent. Clinical responders (decrease in 9-point Mayo score, including ≥2 points and ≥35% from baseline with either a decrease of rectal bleeding subscore of ≥1 or a rectal bleeding subscore of 0 or 1) at week 12 who had received mirikizumab were randomly assigned to groups that received maintenance treatment with mirikizumab 200 mg subcutaneously every 4 weeks (N = 47) or every 12 weeks (N = 46). The primary endpoint was clinical remission (Mayo subscores of 0 for rectal bleeding, with 1-point decrease from baseline for stool frequency, and 0 or 1 for endoscopy) at week 12. A multiple testing procedure was used that began with the 600-mg dose group, and any nonsignificant comparison result ended the formal statistical testing procedure.

RESULTS

At week 12, 15.9% (P = .066), 22.6% (P = .004), and 11.5% (P = .142) of patients in the 50-mg, 200-mg, and 600-mg groups achieved clinical remission, respectively, compared with 4.8% of patients given placebo. The primary endpoint was not significant (comparison to 600 mg, P > .05). Clinical responses occurred in 41.3% (P = .014), 59.7% (P < .001), and 49.2% (P = .001) of patients in the 50-mg, 200-mg, and 600-mg groups, respectively, compared with 20.6% of patients given placebo. At week 52, 46.8% of patients given subcutaneous mirikizumab 200 mg every 4 weeks and 37.0% given subcutaneous mirikizumab 200 mg every 12 weeks were in clinical remission.

CONCLUSIONS

In a randomized trial of patients with UC, mirikizumab was effective in inducing a clinical response after 12 weeks. Additional studies are required to determine the optimal dose for induction of remission. Mirikizumab showed durable efficacy throughout the maintenance period. Clinicaltrials.gov, Number NCT02589665.

Role of innate lymphoid cells in chronic colitis during anti-IL-17A therapy

IL-17A is an important cytokine in intestinal inflammation. However, anti-IL-17A therapy does not improve clinical outcomes in patients with Crohn's disease. We aimed to evaluate the role of RORγt+ innate lymphoid cells (ILCs) in murine colitis models in the absence of IL-17A. An acute colitis model was induced with either dextran sulfate sodium (DSS) or trinitrobenzenesulfonic acid (TNBS) and a chronic colitis model was induced by CD4+CD45RBhi T cell transfer from either wild-type C57BL/6 or Il17a-/- mice. An anti-IL-17A antibody, secukinumab, was also used to inhibit IL-17A function in the colitis model. Flow cytometry was performed to analyze the population of RORγt+ ILCs in the colonic lamina propria of mice with chronic colitis. Acute intestinal inflammation due to DSS and TNBS was attenuated in IL-17A knockout mice, whereas chronic colitis was not relieved by T cell transfer from Il17a-/- mice (% of original body weight: wild-type mice vs. Il17a-/- mice, 81.9% vs. 82.2%; P = 0.922). However, the mean proportion of Lin-RORγt+ lymphocytes was higher after T cell transfer from Il17a-/- mice than that after T cell transfer from wild-type mice (28.8% vs. 18.5%). The proportion of Lin-RORγt+ was also increased in Rag2-/- mice that received T cell transfer from wild-type mice when anti-IL-17A antibody was administered (31.7%). Additionally, Il6 and Il22 tended to be highly expressed after T cell transfer from Il17a-/- mice. In conclusion, RORγt+ ILCs may have an important role in the pathogenesis of chronic colitis in the absence of IL-17A. Blocking the function of IL-17A may upregulate Il6 and recruit RORγt+ ILCs in chronic colitis, thereby upregulating IL-22 and worsening the clinical outcomes of patients with Crohn's disease.

Molecular control of pathogenic Th17 cells in autoimmune diseases

IL-17A-producing CD4⁺ T helper cells (Th17) are crucial for the development of inflammatory and autoimmune diseases and thus are exploited for clinical immunotherapies. Emerging evidence suggests Th17 cells are heterogeneous and able to adopt both pathogenic and non-pathogenic phenotypes which are shaped by environmental and genetic factors. On one hand, IL-6 in concert with TGFβ1 can induce non-pathogenic Th17 cells (non-pTh17), which are not effective in inducing tissue inflammation. On the other hand, IL-6, IL-1β with IL-23 induce pathogenic Th17 cells (pTh17) to induce immune pathologies in various tissues. Th17 cells could be both pathogenic and non-pathogenic in a content-dependent manner in vivo. Understanding how the generation and pathogenicity of pTh17 cells are regulated will aid us to devise more effective immunotherapy. In this review, we summarize recent advances in the differentiation and regulation of Th17 cells especially pTh17 cells in vitro and in vivo. The emerging results revealing the specific molecular control of pTh17 cells are highlighted.

Interrogating host immunity to predict treatment response in inflammatory bowel disease

IBD treatment is undergoing a transformation with an expanding repertoire of drugs targeting different aspects of the immune response. Three novel classes of drugs have emerged in the past decade that target leukocyte trafficking to the gut (vedolizumab), neutralize key cytokines with antibodies (ustekinumab) and inhibit cytokine signalling pathways (tofacitinib). In advanced development are other drugs for IBD, including therapies targeting other cytokines such as IL-23 and IL-6. However, all agents tested so far are hampered by primary and secondary loss of response, so it is desirable to develop personalized strategies to identify which patients should be treated with which drugs. Stratification of patients with IBD by clinical parameters alone lacks sensitivity, and alternative modalities are now needed to deliver precision medicine in IBD. High-resolution profiling of immune response networks in individual patients is a promising approach and different technical platforms, including in vivo real-time molecular endoscopy, tissue transcriptomics and germline genetics, are promising tools to help predict responses to specific therapies. However, important challenges remain regarding the clinical utility of these technologies, including their scalability and accessibility. This Review focuses on unravelling some of the complexity of mucosal immune responses in IBD pathogenesis and how current and emerging analytical platforms might be harnessed to effectively stratify and individualise IBD therapy.

A prospective study comparing patient-reported outcomes in Crohn's disease

BACKGROUND

Patient reported outcomes are important in Crohn's disease. In this prospective cohort, we investigated the performance of the Bristol Stool Form Scale (BSFS) and a visual analog scale (VAS) for abdominal pain as outcome measures in Crohn's disease.

METHODS

Patients with active Crohn's disease starting glucocorticoids or anti-tumor necrosis factor were included. Before treatment and 10 weeks later we collected: clinical activity [Harvey Bradshaw Index (HBI) and Crohn's-Disease-Activity-Index (CDAI)], serum C-reactive protein (CRP) and fecal calprotectin, and BSFS (1-7) and a 100-mm VAS based on a 7-day diary. Clinical response was defined as a reduction by at least 3 and at least 100 of HBI and CDAI, respectively. Fecal calprotectin-response and CRP-response were defined as reduction of at least 50%.

RESULTS

Thirty-eight patients completed follow-up. At baseline, BSFS-parameters correlated more strongly with clinical activity (range: rs: 0.31-0.74) than with CRP (rs: -0.01 to 0.16) and fecal calprotectin (rs: 0.14-0.26). VAS scores correlated very weakly to moderately with clinical activity (rs: 0.18-0.45), and weakly to moderately with CRP (rs: 0.24-0.34) and fecal calprotectin (rs: 0.35-0.43). Changes in VAS scores correlated moderately to strongly (rs: 0.55-0.71) with changes in clinical activity, and weakly with changes in CRP and fecal calprotectin (rs: 0.21-0.35). Changes in BSFS parameters correlated weakly to moderately (rs: 0.23-0.53) with changes in clinical activity, and very weakly to weakly (rs: 0.01-0.35) with changes in CRP and fecal calprotectin. Responsiveness of VAS and BSFS was moderate to high (Guyatt's statistic 0.41-2.17) and highly dependent on the definition of response.

CONCLUSIONS

The BSFS and a VAS appear to be responsive with moderate-to-strong construct validity to monitor patients with Crohn's disease.

Anti-interleukin-23 agents for the treatment of ulcerative colitis

Introduction: Treatment of ulcerative colitis (UC) aims to control symptoms and to suppress intestinal inflammation. Despite considerable advances, a proportion of patients do not respond to currently available drugs. The interleukin (IL)-23 axis plays a significant role in the pathogenesis of UC and has thus become an important target for drug development.Areas covered: The review briefly summarizes the pathophysiology of the IL-12/23 axis and provides a synopsis of the available evidence for efficacy and safety of ustekinumab, mirikizumab (LY3074828), risankizumab (BI655066/ABBV066), brazikumab (MEDI2070; formerly AMG139) and guselkumab (CNTO1959) in UC. We also provide an overview of ongoing and anticipated trials in this field.Expert opinion: A Phase 2 trial with mirikizumab and a Phase 3 trial with ustekinumab have demonstrated the efficacy of anti-IL-23 agents in achieving clinical and endoscopic outcomes in UC with a favorable safety profile. Trials of other anti-IL-23 agents in UC are under way and designed to explore head-to-head efficacy with existing biologics, as well as the prospect of combination biological therapy. Apart from data on longer term efficacy and safety, future trials should also explore strategies to inform the positioning of IL-23 antagonists in therapeutic algorithms.

Evaluation of cytokine levels as putative biomarkers to predict the pharmacological response to biologic therapy in inflammatory bowel diseases

Cytokines play a central role in the pathogenesis of inflammatory bowel diseases. For this reason, the vast majority of biological therapies are aimed to block pro-inflammatory cytokines or their receptors. Although these drugs have modified the course of the disease due to their efficacy, a high rate of non-response or loss of response over time is still an important issue for clinicians. In this perspective, many studies have been conducted in recent years to individuate a reliable biomarker of therapeutic response. In this review, we discuss the role of cytokines involved in the pathogenesis and in the therapy of inflammatory bowel diseases, and their putative use as pharmacological biomarkers of therapy responsiveness.

Rapid Induction and Maintenance of Remission in Refractory Ulcerative Colitis with Ustekinumab

Ulcerative colitis is a chronic debilitating disease characterized by relapsing in intestinal inflammation and ulcers with no available cure. This is a clinical case report of a 52-year-old female patient with 30 years history of left-sided chronic ulcerative colitis controlled with standard of care (mesalamine and azathioprine) which subsequently relapsed and developed into active refractory ulcerative colitis. The patient became unresponsive to her medications including different forms of mesalamines and did not respond favorably to any of the other current therapies. Numerous attempts to stabilize her condition with immunosuppressants, steroids, probiotics, antibiotics, mesalamines, and various biologic agents failed to improve her clinical symptoms, and the patient was being considered for colectomy. As the last resort, modified therapy was prescribed with ustekinumab, a non-selective, anti-IL12/23 p40 monoclonal antibody. This medication has not been yet approved for use in ulcerative colitis patients. In this clinical case we report the efficacy of ustekinumab to rapidly induce and maintain remission of the severe chronic ulcerative colitis in the patient. To the best of our knowledge, this is the first report of utilizing ustakinamub therapy for rapid induction in an active refractory ulcerative colitis patient resulting in complete remission for over one year.

Resolution of Crohn's disease

Crohn's disease (CD) is characterized by chronic inflammation of the gastrointestinal tract and represents one of the main inflammatory bowel disease (IBD) forms. The infiltration of immune cells into the mucosa and uncontrolled production of pro-inflammatory cytokines and other mediators trigger the chronic inflammatory reaction in the intestine [1]. The inflammatory setting consists of subsequent events that comprise an induction phase, the peak of inflammation which is subsequently followed by the resolution phase. The induction phase, which represents the first phase of inflammation, is important for the rapid and efficient activation of the immune system for sufficient host defense. The permanent sensing of exogenous or endogenous danger signals enables the fast initiation of the inflammatory reaction. The immune cell infiltrate initiates an inflammatory cascade where released lipid and protein mediators play an indispensable role [2, 3]. The last decades of research strongly suggest that resolution of inflammation is similarly a tightly coordinated and active process. The basic concept that resolution of inflammation has to be regarded as an active process has been thoroughly described by others [4-6]. The following review focuses on mechanisms, pathways, and specific mediators that are actively involved in the resolution of inflammation in CD.

Immunoproteasome Inhibition Selectively Kills Human CD14+ Monocytes and as a Result Dampens IL-23 Secretion

MECL-1 (β2i), LMP2 (β1i), and LMP7 (β5i) are the proteolytically active subunits of the immunoproteasome (IP), a special type of proteasome mainly expressed in hematopoietic cells. Targeting the IP in autoimmune diseases proved to be therapeutically effective in preclinical mouse models. In endotoxin-stimulated human PBMCs, IP inhibition reduces the secretion of several proinflammatory cytokines, with the suppression of IL-23 being the most prominent. In this study, we investigated why the production of IL-23, a key mediator of inflammation in autoimmunity, is blocked when the IP is inhibited in LPS-stimulated human PBMCs. CD14⁺ monocytes could be identified as the main producers of IL-23 in LPS-stimulated PBMCs. We found that IP inhibition with the irreversible LMP7/LMP2 inhibitor ONX 0914 induced apoptosis in CD14⁺ monocytes, whereas CD4⁺, CD3⁺, CD19⁺, and CD56⁺ cells remained unaffected. A high expression of IPs renders monocytes susceptible to IP inhibition, leading to an accumulation of polyubiquitylated proteins and the induction of the unfolded protein response. Similar to IP inhibition, inducers of the unfolded protein response selectively kill CD14⁺ monocytes in human PBMCs. The blockage of the translation in CD14⁺ monocytes protects these cells from ONX 0914-induced cell death, indicating that the IP is required to maintain protein turnover in monocytes. Taken together, our data reveal why IP inhibition is particularly effective in the suppression of IL-23-driven autoimmunity.

Bedside to bench: defining the immunopathogenesis of psoriatic arthritis

Psoriatic arthritis (PsA) is an immune-mediated, systemic inflammatory disorder. PsA can present with heterogeneous clinical features. Advances in understanding the immunopathogenesis of PsA have helped to facilitate the development of agents targeting specific components of the dysregulated inflammatory and immune responses relevant to PsA. Interestingly, agents with distinct mechanisms of action have shown differential responses across the various disease domains of PsA, counter to what might have been expected from basic science investigations. Here, we review data utilizing various novel targeted therapies for PsA, focusing on biologic and targeted synthetic therapies. These data might support the idea of a 'bedside to bench' concept, whereby results from clinical trials of specific targeted therapies inform our understanding of the immunopathogenesis of PsA. For example, TNF inhibition confers substantial and comparable benefit for all domains of PsA, supporting the view that TNF is a central pro-inflammatory cytokine across diverse areas of disease involvement. On the other hand, inhibition of IL-12-IL-23, as compared with inhibition of TNF, has greater efficacy for psoriasis, comparable efficacy for peripheral arthritis, but was ineffective in studies of axial spondyloarthritis. Data from studies of agents with distinct mechanisms of action will help to further refine our understanding of the immunopathogenesis of PsA.

Inflammatory cytokines: from discoveries to therapies in IBD

Introduction: Although the etiology of inflammatory bowel diseases (IBD) remains unknown, accumulating evidence suggests that the intestinal tissue damage in these disorders is due to a dynamic interplay between immune cells and non-immune cells, which is mediated by cytokines produced within the inflammatory microenvironment. Areas covered: We review the available data about the role of inflammatory cytokines in IBD pathophysiology and provide an overview of the therapeutic options to block the function of such molecules. Expert opinion: Genome studies, in vitro experiments with patients' samples and animal models of colitis, have largely advanced our understanding of how cytokines modulate the ongoing mucosal inflammation in IBD. However, not all the cytokines produced within the damaged gut seem to play a major role in the amplification and perpetuation of the IBD-associated inflammatory cascade. Indeed, while some of the anti-cytokine compounds are effective in some subgroups of IBD patients, others have no benefit. In this complex scenario, a major unmet need is the identification of biomarkers that can predict response to therapy and facilitate a personalized therapeutic approach, which maximizes the benefits and limits the adverse events.

Translating Immunology into Therapeutic Concepts for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) defines a spectrum of complex disorders. Understanding how environmental risk factors, alterations of the intestinal microbiota, and polygenetic and epigenetic susceptibility impact on immune pathways is key for developing targeted therapies. Mechanistic understanding of polygenic IBD is complemented by Mendelian disorders that present with IBD, pharmacological interventions that cause colitis, autoimmunity, and multiple animal models. Collectively, this multifactorial pathogenesis supports a concept of immune checkpoints that control microbial-host interactions in the gut by modulating innate and adaptive immunity, as well as epithelial and mesenchymal cell responses. In addition to classical immunosuppressive strategies, we discuss how resetting the microbiota and restoring innate immune responses, in particular autophagy and epithelial barrier function, might be key for maintaining remission or preventing IBD. Targeting checkpoints in genetically stratified subgroups of patients with Mendelian disorder-associated IBD increasingly directs treatment strategies as part of personalized medicine.

Temporally Distinct Functions of the Cytokines IL-12 and IL-23 Drive Chronic Colon Inflammation in Response to Intestinal Barrier Impairment

Epithelial barrier defects are implicated in the pathogenesis of inflammatory bowel disease (IBD); however, the role of microbiome dysbiosis and the cytokine networks orchestrating chronic intestinal inflammation in response to barrier impairment remain poorly understood. Here, we showed that altered Schaedler flora (ASF), a benign minimal microbiota, was sufficient to trigger colitis in a mouse model of intestinal barrier impairment. Colitis development required myeloid-cell-specific adaptor protein MyD88 signaling and was orchestrated by the cytokines IL-12, IL-23, and IFN-γ. Colon inflammation was driven by IL-12 during the early stages of the disease, but as the mice aged, the pathology shifted toward an IL-23-dependent inflammatory response driving disease chronicity. These findings reveal that IL-12 and IL-23 act in a temporally distinct, biphasic manner to induce microbiota-driven chronic intestinal inflammation. Similar mechanisms might contribute to the pathogenesis of IBD particularly in patients with underlying intestinal barrier defects.

Mechanism-Based Treatment Strategies for IBD: Cytokines, Cell Adhesion Molecules, JAK Inhibitors, Gut Flora, and More

Background

Although TNF inhibitors revolutionized the therapy of inflammatory bowel disease (IBD), we have been reaching a point where other therapies with different mechanisms of action are necessary. A rising number of elderly IBD patients with contraindications to established therapies and a growing group of patients losing response to anti-TNF therapy compel us to find safer, better-tolerated, and, ideally, personalized treatment options. However, in order to choose the right drug to fit a patient, it is indispensable to understand the pathomechanism involved in IBD.

Summary

The aim of this review is to explain the inflammatory signaling pathways in IBD and how to inhibit them with current and future therapeutic approaches. Next to biologic agents targeting inflammatory cytokines (anti-TNF agents, anti-IL-12/-23 agents, and specific inhibitors of IL-23), biologics blocking leukocyte trafficking to the gut (anti-integrin antibodies) are available nowadays. More recently, small molecules inhibiting the JAK-STAT pathway (JAK inhibitors) or preventing lymphocyte trafficking (sphingosine-1-phosphate modulators) have been approved or are under investigation. Furthermore, modifying the microbiota has potential therapeutic effects on IBD, and autologous hematopoietic or mesenchymal stem cell transplantation may be considered for a highly selected group of IBD patients.

Key Message

Physicians should understand the different mechanisms of action of the potential therapies for IBD to select the right drug for the right patient.

Targeting immune cell circuits and trafficking in inflammatory bowel disease

Inflammatory bowel diseases (IBDs) such as Crohn's disease and ulcerative colitis are characterized by uncontrolled activation of intestinal immune cells in a genetically susceptible host. Due to the progressive and destructive nature of the inflammatory process in IBD, complications such as fibrosis, stenosis or cancer are frequently observed, which highlights the need for effective anti-inflammatory therapy. Studies have identified altered trafficking of immune cells and pathogenic immune cell circuits as crucial drivers of mucosal inflammation and tissue destruction in IBD. A defective gut barrier and microbial dysbiosis induce such accumulation and local activation of immune cells, which results in a pro-inflammatory cytokine loop that overrides anti-inflammatory signals and causes chronic intestinal inflammation. This Review discusses pathogenic cytokine responses of immune cells as well as immune cell trafficking as a rational basis for new translational therapies in IBD.

Novel Pharmacological Therapy in Inflammatory Bowel Diseases: Beyond Anti-Tumor Necrosis Factor

Inflammatory bowel diseases (IBDs) are chronic conditions of the gastrointestinal tract in which dysregulated immune responses cause persistent inflammation of the gut mucosa. Biologic therapy with anti-TNF blockers has revolutionized the therapeutic management of IBD for their remarkable efficacy and potential impact on disease course and for many years has represented the sole treatment option for patients refractory or intolerant to conventional therapy. In recent years, more molecules, both biologically and chemically synthetized, have been developed as potential therapeutic options for IBD that target different molecular pathways aside from TNF blockade, and which have been proposed as targets for novel drugs. This is particularly relevant for the present, as well as future, management of IBD, considering that some patients are refractory to anti-TNF. This review will summarize the pharmacological options, either currently available or in the pipeline, for market approval to treat IBD, besides anti-TNF strategies, based on their mechanism(s) of action. We will also analyze the current evidence for effectiveness and safety, as well as offer perspective, regarding the potential implementation for such therapies in the future.

The IBD Management Puzzle: Do We Have All the Pieces?

The management of inflammatory bowel disease (IBD) has entered an exciting era, with the optimisation of existing therapies, new strategies being explored that have the potential to further improve patient outcomes, and a growing recognition of the value of a personalised approach to treatment. This symposium explored optimal approaches to using biologic therapy, and the use of therapeutic drug monitoring (TDM) and biomarkers in treatment management. IBD shows a progressive immunopathogenesis, and a ‘window of opportunity’ exists whereby early intervention may alter the disease course. There is a convincing body of evidence supporting early intervention with anti-TNF-α therapies to improve patient outcomes. Cost is the major barrier to initiating and continuing treatment with biologic therapy. Biosimilars have the potential to reduce costs and increase patient access to biologic therapies, enabling more patients to receive biologic treatment earlier. The use of TDM in the treatment of IBD is increasing and offers benefits over standardised approaches to dosing, and it is likely that emerging dose optimisation tools will enable a personalised approach to treatment in the future. Many patients experience loss of response to anti-TNF-α therapy. Biomarkers currently used to monitor treatment response include C reactive protein (CRP), faecal calprotectin, and anti-drug antibodies (ADA). Although biomarker identification is still at an early stage for IBD, several genetic, serological, and microbiome markers have also shown promise in predicting response to anti-TNF-α therapy, while other biomarkers are also under investigation for use in diagnosis, predicting response to therapy, and treatment monitoring.

New biologics and small molecules in inflammatory bowel disease: an update

Inflammatory bowel disease (IBD) is a spectrum of immune-mediated inflammatory disorders with a complex multifactorial pathogenesis, where different pathways may predominate in different individuals. This complexity will most likely require a panoply of drugs targeting different pathways if one wants to treat to steroid-free sustained remission and mucosal healing. Presently, the mainstay of medical management of IBD is based on 5-aminosalicylates, corticosteroids, thiopurines, methotrexate, antitumor necrosis factor, anti-alpha4 beta7 (α4β7) integrin and anti-interleukin (IL)-12/IL-23 therapies. The discovery of new pathways involved in the pathogenesis of IBD resulted in new drugs targeting Janus kinase/signal transducers and activators of transcription, IL-6, spingosine-1-phosphate, and phosphodiesterase 4, among others. These new therapies might result in more advantageous safety profiles. Several of these new drugs have already been successfully tested in other inflammatory disorders, such as psoriasis or rheumatoid arthritis. In this review, evidence from phase II and phase III randomized controlled clinical trials in patients with IBD involving new biologicals and small molecules are summarized.

Innate Lymphoid Cells in Mucosal Immunity

Innate lymphoid cells (ILCs) are innate counterparts of T cells that contribute to immune responses by secreting effector cytokines and regulating the functions of other innate and adaptive immune cells. ILCs carry out some unique functions but share some tasks with T cells. ILCs are present in lymphoid and non-lymphoid organs and are particularly abundant at the mucosal barriers, where they are exposed to allergens, commensal microbes, and pathogens. The impact of ILCs in mucosal immune responses has been extensively investigated in the gastrointestinal and respiratory tracts, as well as in the oral cavity. Here we review the state-of-the-art knowledge of ILC functions in infections, allergy and autoimmune disorders of the mucosal barriers.

Expansion of IL-23 receptor bearing TNFR2+ T cells is associated with molecular resistance to anti-TNF therapy in Crohn's disease

OBJECTIVE

Anti-tumour necrosis factor (TNF) antibodies are successfully used for treatment of Crohn's disease. Nevertheless, approximately 40% of patients display failure to anti-TNF therapy. Here, we characterised molecular mechanisms that are associated with endoscopic resistance to anti-TNF therapy.

DESIGN

Mucosal and blood cells were isolated from patients with Crohn's disease prior and during anti-TNF therapy. Cytokine profiles, cell surface markers, signalling proteins and cell apoptosis were assessed by microarray, immunohistochemistry, qPCR, ELISA, whole organ cultures and FACS.

RESULTS

Responders to anti-TNF therapy displayed a significantly higher expression of TNF receptor 2 (TNFR2) but not IL23R on T cells than non-responders prior to anti-TNF therapy. During anti-TNF therapy, there was a significant upregulation of mucosal IL-23p19, IL23R and IL-17A in anti-TNF non-responders but not in responders. Apoptosis-resistant TNFR2+IL23R+ T cells were significantly expanded in anti-TNF non-responders compared with responders, expressed the gut tropic integrins α4β7, and exhibited increased expression of IFN-γ, T-bet, IL-17A and RORγt compared with TNFR2+IL23R- cells, indicating a mixed Th1/Th17-like phenotype. Intestinal TNFR2+IL23R+ T cells were activated by IL-23 derived from CD14+ macrophages, which were significantly more present in non-responders prior to anti-TNF treatment. Administration of IL-23 to anti-TNF-treated mucosal organ cultures led to the expansion of CD4+IL23R+TNFR2+ lymphocytes. Functional studies demonstrated that anti-TNF-induced apoptosis in mucosal T cells is abrogated by IL-23.

CONCLUSIONS

Expansion of apoptosis-resistant intestinal TNFR2+IL23R+ T cells is associated with resistance to anti-TNF therapy in Crohn's disease. These findings identify IL-23 as a suitable molecular target in patients with Crohn's disease refractory to anti-TNF therapy.

Two distinct colonic CD14+ subsets characterized by single-cell RNA profiling in Crohn's disease

Inflammatory bowel diseases are associated with dysregulated immune responses in the intestinal tissue. Four molecularly identified macrophage subsets control immune homeostasis in healthy gut. However, the specific roles and transcriptomic profiles of the phenotypically heterogeneous CD14⁺ macrophage-like population in inflamed gut remain to be investigated in Crohn's disease (CD). Here we identified two phenotypically, morphologically and functionally distinct colonic HLADR⁺SIRPα⁺CD14⁺ subpopulations that were further characterized using single-cell RNA-sequencing (scRNAseq) in CD. Frequencies of CD64^hiCD163^-/dim cells selectively augmented in inflamed colon and correlated with endoscopic score of disease severity. IL-1β and IL-23-producing CD64^hiCD163^-/dim cells predominated over TNF-α-producing CD64^hiCD163^hi cells in lesions. Purified "inflammatory monocyte-like" CD163^-, but not "macrophage-like" CD163^hi cells, through IL-1β, promoted Th17/Th1 but not Th1 responses in tissue memory CD4⁺T cells. Unsupervised scRNAseq analysis that captures the entire HLADR⁺SIRPα⁺ population revealed six clusters, two of which were enriched in either CD163^- or CD163^hi cells, and best defined by TREM1/FCAR/FCN1/IL1RN or CD209/MERTK/MRCI/CD163L1 genes, respectively. Selected newly identified discriminating markers were used beyond CD163 to isolate cells that shared pro-Th17/Th1 function with CD163^- cells. In conclusion, a molecularly distinct pro-inflammatory CD14⁺ subpopulation accumulates in inflamed colon, drives intestinal inflammatory T-cell responses, and thus, might contribute to CD disease severity.

Mechanisms of molecular resistance and predictors of response to biological therapy in inflammatory bowel disease

Biological therapy has led to marked improvements in treatment of patients with inflammatory bowel disease, and an increasing number of drugs has been approved for treatment. However, only a subgroup of patients responds to therapy, highlighting the need to identify biomarkers for therapeutic response to allow personalised medicine in inflammatory bowel disease. Potential markers of response to biological therapy have been identified; however, studies also suggest that changes in the composition of immune cell infiltrates in response to therapeutic pressure lead to molecular resistance to these drugs. For instance, the cytokine interleukin 23 has been identified as a driver of evasion of apoptosis in response to anti-tumour necrosis factor drugs in patients with Crohn's disease, leading to expansion of apoptosis-resistant T cells and drug resistance. In this Review, we examine the concept of molecular resistance to biological therapy and discuss implications for future therapy.